Integrin Β1 Signaling Pathway Research Articles

Prolactin-induced protein in breast cancer.

Prolactin-induced protein (PIP) is a 17-kDa single polypeptide chain that is secreted by a number of normal apocrine cells, such as milk, saliva, and seminal fluid. PIP is widely expressed in breast cancer and is commonly used as a diagnostic biomarker for the histopathological diagnosis of this disease. Expression of PIP in breast cancer is regulated by androgen and prolactin through a number of transcription factors and signaling cross-talks, including STAT5, Runx2, and CREB1. Notably, PIP is induced by a positive feedback loop between androgen receptor (AR) and extracellular signal-regulated kinase (ERK). The available data indicate that PIP has an aspartyl protease activity that can degrade fibronectin. Importantly, PIP is necessary for outside-in activation of integrin-β1 signaling pathway and regulation of key downstream signaling targets of this pathway such as interaction of integrin-β1 with integrin-linked kinase 1 (ILK1) and ErbB2. Furthermore, the importance of PIP in cell proliferation has been demonstrated by the fact that purified PIP promotes growth of breast cancer cells and PIP expression is necessary for the proliferation of T-47D and MDA-MB-453 cell lines. In addition to cell proliferation, PIP mediates invasion of breast cancer cells in a process that partially depends on the degradation of fibronectin by this protein. Therefore, PIP is a breast cancer-related protein that is expressed in a majority of breast tumors and has a significant function in the biology of this disease.

ET-70 * COMBINATION OF oHSV WITH INTEGRIN 1 NEUTRALIZING ANTIBODY (OS2966) AUGMENTS oHSV THERAPY

Oncolytic HSV (oHSV) is a biologic therapy currently being tested in patients. We have previously shown that oHSV-induced Cysteine-rich 61 protein (CCN1) binds with integrin α6β1, activating a type 1 IFN-antiviral defense response. oHSV-induced CCN1 induction also increases macrophage infiltration and activation, resulting in increased virus clearance in glioblastoma cells. Integrin β1 is cell surface molecule involved in multiple functions like cellular proliferation, invasion and inflammation. Inhibition of integrin β1 has shown anti-tumor efficacy in preclinical modles of glioma. Furthermore, incorporating the Rembrandt database of the National Cancer Institute, we found integrin β1 expression is negatively associated with glioblastoma patient survival (p value < 0.0001). Interestingly, oHSV infection strongly increased integrin β1 expression (western blot). Based on this, we hypothesized that the combination of oHSV with integrin β1neutralizing antibody (OS2966) will augment oHSV therapy. Combination treatment with OS2966 increased oHSV replication and cell killing. Increased viral replication and cell killing was more obvious in the laminin-coated cells, consistent with integrin β1 signaling pathway. OS2966 treatment strongly inhibited oHSV-induced raw246.7 macrophage cell migration towards infected glioblastoma cells as dose dependent manner (migration assay). Inhibition of integrin β1in glioma cell lines and patient derived primary GSCs significantly increased markers of sensencsence such as enhanced β-gal activity, along with induction of p21, and reduction of phosphorylation of AKT and Rb, indicating that integrin β1 activation is involved in self-renewal, and proliferation. In conclusion, oHSV-induced integrin β1 expression sensitize to OS2966 effect, resulting in enhanced viral replication and inhibition of macrophage migration. Our findings reveal how integrin β1 limits oHSV replication. Our findings also reveal how OS2966, an integrin β1 blocking antibody which has been humanized in anticipation of potential clinical trials, inhibits the innate immune response elicited upon oHSV therapy. The results will lead to the development of a novel oHSV therapeutic strategy.

The Activation of &amp;#946;&lt;sub&gt;1&lt;/sub&gt;-integrin by Type I Collagen Coupling with the Hedgehog Pathway Promotes the Epithelial-Mesenchymal Transition in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by the excessive deposition of extracellular matrix (ECM), which is thought to contribute to this tumor's malignant behavior. However, the detailed mechanism and the contribution of excessive deposition of ECM in PDAC progression remain unclear. A better understanding of the mechanism involved in this process is essential for the design of new effective therapies. In this study, we demonstrated that pancreatic cancer cells exhibited increased proliferation and decreased apoptosis in response to type I collagen. In addition, PDAC cells exposed to type I collagen lost the expression of E-cadherin and increased expression of mesenchymal markers, including N-cadherin and vimentin. This epithelial- mesenchymal transition (EMT) was correlated with enhanced cell migration and invasiveness. Knockdown of β1-integrin abolished the effects induced by type I collagen, and further investigation revealed that type I collagen activates β1-integrin (marked by phosphorylation of β1 integrin downstream effectors, focal adhesion kinase [FAK], AKT, and ERK) accompanied by markedly up-regulation of Gli-1, a component of the Hedgehog (HH) pathway. Knockdown of Gli-1 reversed the effects of type I collagen on PDAC invasion and EMT. These results suggest that there is cross-talk between the β1-integrin signaling pathway and the HH pathway in pancreatic cancer and that activation of the HH pathway plays a key role in the type I collagen-induced effects on pancreatic cancer.

The diacylglycerol kinase α/atypical PKC/β1 integrin pathway in SDF-1α mammary carcinoma invasiveness.

Diacylglycerol kinase α (DGKα), by phosphorylating diacylglycerol into phosphatidic acid, provides a key signal driving cell migration and matrix invasion. We previously demonstrated that in epithelial cells activation of DGKα activity promotes cytoskeletal remodeling and matrix invasion by recruiting atypical PKC at ruffling sites and by promoting RCP-mediated recycling of α5β1 integrin to the tip of pseudopods. In here we investigate the signaling pathway by which DGKα mediates SDF-1α-induced matrix invasion of MDA-MB-231 invasive breast carcinoma cells. Indeed we showed that, following SDF-1α stimulation, DGKα is activated and localized at cell protrusion, thus promoting their elongation and mediating SDF-1α induced MMP-9 metalloproteinase secretion and matrix invasion. Phosphatidic acid generated by DGKα promotes localization at cell protrusions of atypical PKCs which play an essential role downstream of DGKα by promoting Rac-mediated protrusion elongation and localized recruitment of β1 integrin and MMP-9. We finally demonstrate that activation of DGKα, atypical PKCs signaling and β1 integrin are all essential for MDA-MB-231 invasiveness. These data indicates the existence of a SDF-1α induced DGKα - atypical PKC - β1 integrin signaling pathway, which is essential for matrix invasion of carcinoma cells.

SERPINA5 inhibits tumor cell migration by modulating the fibronectin–integrin β1 signaling pathway in hepatocellular carcinoma

In our previous study, we identified 1241 loci with somatic copy number alterations in human hepatocellular carcinoma (HCC) using Affymetrix SNP 6.0 arrays, and a putative cancer gene SERPINA5 was uncovered in a novel chromosomal region with recurrent copy number loss at 14q31.1–32.13. The SERPINA5 was reported to be deregulated in renal, breast, prostate and ovarian cancers. However, the roles of SERPINA5 in cancer remain greatly elusive. In this study, we found that the DNA dosage and expression level of the SERPINA5 gene were significantly decreased in HCC by quantitative real-time PCR. Notably, the expression levels of SERPINA5 negatively correlated with malignant progression of HCC. The SERPINA5 gene was further observed to reduce in vitro and in vivo metastatic potential of HCC cells. Moreover, secreted SERPINA5 protein also could inhibit the metastatic ability of HCC cells. Finally, we discovered that one of the mechanisms explaining SERPINA5 inhibition of HCC metastasis is through direct interaction with fibronectin and disruption of the fibronectin–integrin signaling pathway. These findings highlight an important role of SERPINA5 in the regulation of migratory and metastatic potentials of HCC and suggest a potential application of SERPINA5 in cancer treatment.

CYLD Inhibits Melanoma Growth and Progression through Suppression of the JNK/AP-1 and β1-Integrin Signaling Pathways

The molecular mechanisms mediating CYLD tumor suppressor function appear to be manifold. Here, we demonstrated that, in contrast to the increased levels of pJNK, CYLD was decreased in a majority of melanoma cell lines and tissues examined. Exogenous expression of CYLD but not its catalytically deficient mutant markedly inhibited melanoma cell proliferation and migration in vitro and subcutaneous tumor growth in vivo. In addition, the melanoma cells expressing exogenous CYLD were unable to form pulmonary tumor nodules following tail-vein injection. At the molecular level, CYLD decreased β1-integrin and inhibited pJNK induction by TNFα or cell-attachment to collagen IV. Moreover, CYLD induced an array of other molecular changes associated with modulation of the ‘malignant’ phenotype, including a decreased expression of cyclin D1, N-cadherin and nuclear Bcl3, and an increased expression of p53 and E-cadherin. Most interestingly, co-expression of the constitutively active MKK7 or c-Jun mutants with CYLD prevented the above molecular changes, and fully restored melanoma growth and metastatic potential in vivo. Our findings demonstrate that JNK/AP-1 signaling pathway underlies the melanoma growth and metastasis that is associated with CYLD loss-of-function. Thus, restoration of CYLD and inhibition of JNK and β1-integrin function represent potential therapeutic strategies for treatment of malignant melanoma.

The involvement of integrin β1 signaling in the migration and myofibroblastic differentiation of skin fibroblasts on anisotropic collagen-containing nanofibers

Utilization of nanofibrous matrices for skin wound repair holds great promise due to their morphological and dimensional similarity to native extracellular matrix (ECM). It becomes highly desired to understand how various nanofibrous matrices regulate skin cell behaviors and intracellular signaling pathways, important to tuning the functionality of tissue-engineered skin grafts and affecting the wound healing process. In this study, the phenotypic expressions of normal human dermal fibroblasts (NHDFs) on collagen-containing nanofibrous matrices with either isotropic ( i.e., fibers collected randomly with no alignment) or anisotropic ( i.e., fibers collected with alignment) fiber organizations were studied by immunostaining, migration assay and molecular analyses. Results showed that both nanofibrous matrices supported the attachment and growth of NHDFs similarly, while showing different cell morphology with distinct variation in focal adhesion formation and distribution. Anisotropic nanofibers significantly triggered the integrin β1 signaling pathway in NHDFs as evidenced by an increase of active integrin β1 (130 kD mature form) and phosphorylation of focal adhesion kinase (FAK) at Tyr-397. Anisotropic matrices also promoted the migration of NHDFs along the fibers, while neutralization of the integrin β1 activity abolished this promotion. Moreover, the fibroblast-to-myofibroblast differentiation was greatly enhanced for the NHDFs cultured on anisotropic nanofibrous matrices over a period of 48 h. Inhibition of cellular integrin β1 activity by neutralizing antibody eliminated this enhancement. These findings suggest the important role of integrin β1 signaling pathway in regulating the nanofiber-induced fibroblast phenotypic alteration and providing insightful understanding of the possible application of collagen-containing nanofibrous matrices for skin regeneration.

Inhibition of silibinin on migration and adhesion capacity of human highly metastatic breast cancer cell line, MDA-MB-231, by evaluation of β1-integrin and downstream molecules, Cdc42, Raf-1 and D4GDI

Metastasis is a property of malignant cancer cells that requires integrins which with their downstream molecules participate in a number of signaling events in cells with pivotal roles in malignancy, migration and invasion of tumor cells. Silibinin, a flavonoid antioxidant from milk thistle (Silybum marianum L.), has attracted attention in the last decades for chemoprevention and chemotherapy of tumor cells. In the present study, the effect of silibinin on migration and adhesion capacity of MDA-MB-231 cells, a highly metastatic human breast cancer cell line, was investigated by evaluation of β1-integrin and its important downstream molecules. MTT, migration and adhesion assays were performed to evaluate the silibinin effects on proliferation, migration and adhesion of MDA-MB-231 cells. In addition, the influence of the silibinin on the expression of β1-integrin, Raf-1, Cdc42 and D4-GDI mRNAs was assessed by RT-PCR. Results showed significant dose-dependent inhibitory effect of silibinin on proliferation, migration and adhesion of MDA-MB-231 cells. It significantly inhibited the expression of Cdc42 and D4-GDI mRNAs but had no statistically significant effect on the expression of β1-integrin and Raf-1 mRNAs although it indirectly but effectively modulated β1-integrin signaling pathway and RAF1 function. In conclusion, the results showed the silibinin effectson reducing the rate of metastasis, migration and adhesion of MDA-MB-231 to distant organs.

Gambogic acid inhibits tumor cell adhesion by suppressing integrin β1 and membrane lipid rafts-associated integrin signaling pathway

Cell adhesion plays an important role in the steps of cancer metastasis. Regulation of cell–cell (intercellular) and cell–matrix adhesion is a promising strategy for cancer progression. Gambogic acid is a xanthone derived from the resin of the Chinese plant Garciania hanburyi, with potent anti-metastasis activity on highly metastatic cells. The aim of this study was to investigate the function and mechanism of gambogic acid on tumor adhesion. We found that gambogic acid strongly inhibited the adhesion of human cancer cells to fibronectin. This inhibition was associated with the deformation of focal adhesion complex, which was mediated by suppressing the expression of integrin β1 and integrin signaling pathway. In vitro, cell lipid rafts clustering was inhibited following treatment of gambogic acid, which induced the suppression of integrin β1 and focal adhesion complex proteins colocalization within rafts. Moreover, gambogic acid significantly decreased cellular cholesterol content, whereas cholesterol replenishment lessened the inhibitory effect of gambogic acid on cell adhesion. Real-time PCR analysis showed that gambogic acid reduced mRNA levels of hydroxymethylglutaryl-CoA reductase and sterol regulatory element binding protein-2, while increased acetyl-CoA acetyltransferase-1/2. Taken together, these results demonstrate that gambogic acid inhibits cell adhesion via suppressing integrin β1 abundance and cholesterol content as well as the membrane lipid raft-associated integrin function, which provide new evidence for the anti-cancer activity of gambogic acid.

Caveolin 3-mediated integrin β1 signaling is required for the proliferation of folliculostellate cells in rat anterior pituitary gland under the influence of extracellular matrix

Folliculostellate (FS) cells in the anterior pituitary gland are believed to have multifunctional properties. Using transgenic rats that express green fluorescent protein (GFP) specifically in FS cells in the anterior pituitary gland (S100b-GFP rats), we recently revealed that FS cells in primary culture exhibited marked proliferation in the presence of laminin, an extracellular matrix (ECM) component of the basement membrane. In a process referred to as matricrine action, FS cells receive ECM as a signal through their receptors, which results in morphological and functional changes. In this study, we investigated matricrine signaling in FS cells and observed that the proliferation of FS cells is mediated by integrin β1, which is involved in various signaling pathways for cell migration and proliferation in response to ECM. Then, we analyzed downstream events of the integrin β1 signaling pathway in the proliferation of FS cells and identified caveolin 3 as a potential candidate molecule. Caveolin 3 is a membrane protein that binds cholesterol and a number of signaling molecules that interact with integrin β1. Using specific small interfering RNA of caveolin 3, the proliferation of FS cells was inhibited. Furthermore, caveolin 3 drove activation of the mitogen-activated protein kinase (MAPK) signaling cascades, which resulted in upregulation of cyclin D1 in FS cells. These findings suggest that matricrine signaling in the proliferation of FS cells was transduced by a caveolin 3-mediated integrin β1 signaling pathway and subsequent activation of the MAPK pathway.

Yersinia controls type III effector delivery into host cells by modulating Rho activity.

Yersinia pseudotuberculosis binds to β1 integrin receptors, and uses the type III secretion proteins YopB and YopD to introduce pores and to translocate Yop effectors directly into host cells. Y. pseudotuberculosis lacking effectors that inhibit Rho GTPases, YopE and YopT, have high pore forming activity. Here, we present evidence that Y. pseudotuberculosis selectively modulates Rho activity to induce cellular changes that control pore formation and effector translocation. Inhibition of actin polymerization decreased pore formation and YopE translocation in HeLa cells infected with Y. pseudotuberculosis. Inactivation of Rho, Rac, and Cdc42 by treatment with Clostridium difficile toxin B inhibited pore formation and YopE translocation in infected HeLa cells. Expression of a dominant negative form of Rac did not reduce the uptake of membrane impermeable dyes in HeLa cells infected with a pore forming strain YopEHJT−. Similarly, the Rac inhibitor NSC23766 did not decrease pore formation or translocation, although it efficiently hindered Rac-dependent bacterial uptake. In contrast, C. botulinum C3 potently reduced pore formation and translocation, implicating Rho A, B, and/or C in the control of the Yop delivery. An invasin mutant (Y. pseudotuberculosis invD911E) that binds to β1 integrins, but inefficiently transduces signals through the receptors, was defective for YopE translocation. Interfering with the β1 integrin signaling pathway, by inhibiting Src kinase activity, negatively affected YopE translocation. Additionally, Y. pseudotuberculosis infection activated Rho by a mechanism that was dependent on YopB and on high affinity bacteria interaction with β1 integrin receptors. We propose that Rho activation, mediated by signals triggered by the YopB/YopD translocon and from engagement of β1 integrin receptors, stimulates actin polymerization and activates the translocation process, and that once the Yops are translocated, the action of YopE or YopT terminate delivery of Yops and prevents pore formation.

The EphA4 receptor regulates dendritic spine remodeling by affecting β1-integrin signaling pathways

Remodeling of dendritic spines is believed to modulate the function of excitatory synapses. We previously reported that the EphA4 receptor tyrosine kinase regulates spine morphology in hippocampal pyramidal neurons, but the signaling pathways involved were not characterized (Murai, K.K., L.N. Nguyen, F. Irie, Y. Yamaguchi, and E.B. Pasquale. 2003. Nat. Neurosci. 6:153–160). In this study, we show that EphA4 activation by ephrin-A3 in hippocampal slices inhibits integrin downstream signaling pathways. EphA4 activation decreases tyrosine phosphorylation of the scaffolding protein Crk-associated substrate (Cas) and the tyrosine kinases focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) and also reduces the association of Cas with the Src family kinase Fyn and the adaptor Crk. Consistent with this, EphA4 inhibits β1-integrin activity in neuronal cells. Supporting a functional role for β1 integrin and Cas inactivation downstream of EphA4, the inhibition of integrin or Cas function induces spine morphological changes similar to those associated with EphA4 activation. Furthermore, preventing β1-integrin inactivation blocks the effects of EphA4 on spines. Our results support a model in which EphA4 interferes with integrin signaling pathways that stabilize dendritic spines, thus modulating synaptic interactions with the extracellular environment.

Notch, Epidermal Growth Factor Receptor, and β1-Integrin Pathways Are Coordinated in Neural Stem Cells

Notch1 and beta1-integrins are cell surface receptors involved in the recognition of the niche that surrounds stem cells through cell-cell and cell-extracellular matrix interactions, respectively. Notch1 is also involved in the control of cell fate choices in the developing central nervous system (Lewis, J. (1998) Semin. Cell Dev. Biol. 9, 583-589). Here we report that Notch and beta1-integrins are co-expressed and that these proteins cooperate with the epidermal growth factor receptor in neural progenitors. We describe data that suggests that beta1-integrins may affect Notch signaling through 1) physical interaction (sequestration) of the Notch intracellular domain fragment by the cytoplasmic tail of the beta1-integrin and 2) affecting trafficking of the Notch intracellular domain via caveolin-mediated mechanisms. Our findings suggest that caveolin 1-containing lipid rafts play a role in the coordination and coupling of beta1-integrin, Notch1, and tyrosine kinase receptor signaling pathways. We speculate that this will require the presence of the adequate beta1-activating extracellular matrix or growth factors in restricted regions of the central nervous system and namely in neurogenic niches.

826 Magnetic resonance imaging allows early noninvasive assessment of left ventricular remodelling after myocardial infarction in rats

826 Magnetic resonance imaging allows early noninvasive assessment of left ventricular remodelling after myocardial infarction in rats

PKC and ERK1/2 regulate amylase promoter activity during differentiation of a salivary gland cell line.

The addition of transforming growth factor alpha (TGFalpha) to a human submandibular gland cell line (HSG) cultured on basement membrane extract Matrigel, synergistically activates the acinar cell-specific salivary amylase promoter. Signaling through beta1 integrins and increased phosphorylation of ERK1/2 are involved in the increased promoter activity. Phorbol-12-myristate-13-acetate (PMA) and thapsigargin increase amylase promoter activity, suggesting that phorbol ester and calcium-dependent protein kinase C (PKC) pathways are also involved. The combination of specific inhibitors of PKC and MEK1 inhibits the amylase promoter. Inhibitors of the calcium-dependent PKC isoforms alpha, beta, and gamma decrease the promoter activity; however, PKCbeta is not detectable in HSG cells. TGFalpha alters the cellular localization of PKCalpha but not -gamma, suggesting PKCalpha is involved in TGFalpha upregulation of the amylase promoter. Furthermore, rottlerin, a PKCdelta-specific inhibitor, increases the promoter activity, suggesting PKC isoforms differentially regulate the amylase promoter. In conclusion, beta1-integrin and TGFalpha signaling pathways regulate the amylase promoter activity in HSG cells. In response to Matrigel and TGFalpha, the activation of both PKCalpha and phosphorylation of ERK1/2 results in synergistic activation of the amylase promoter. Published 2000 Wiley-Liss, Inc.